Back support for chairs, car seats, and the like



July 31, 1956 ENDRESEN 2,756,809

BACK SUPPORT FOR CHAIRS, CAR SEATS, AND THE LIKE Filed June 50, 1954United States Patent BACK SUPPORT FoReirAiR's, SEATS, AND THE LIKE ErnstEndresen, St'a'vaiiger, Norway Application June 30, 1954, Serial No.440,517

3 Claims. (Cl. 155-182) The invention relates to an improved backsupport for chairs, car seats and the like such as back rests forhospitals, specially designed to counteract and prevent pains in theback, such as sciatica, lumbago and the like, and is concerned primarilywith a back rest of the kind consisting of a relatively stiff plateadapted to follow the lines of the human back and having a lower convexpart and an upper concave or straight part, the curves of the platebeing adjustable by means such as screws which can be manipulated toincrease or decrease the convexity and concavity of the plate to suitthe seated person.

The arrangement according to the present invention is characterized inthat means are provided for moving the ridges of the curvatures in thelongitudinal direction of the plate and for adjustment of the transitioncurve between the shaped parts thereof. Efficient means are therebyobtained whereby the form of the plate can be adjusted in accordancewith the particular contour of the back of the seated person, suchbackline differing from person to person. The back support is speciallydesigned to be placed in the drivers seat of buses and motorcars, butcan also be used in hospitals by being placed in bed for a pa tient tolie on or as a back rest.

One example of the device is shown on the accompanying drawing wherein:

Figure 1 shows a longitudinal section taken on the line 1-1 of Figure 2;

Figure 2 is a front view of Figure l and Figure 3 is a horizontal crosssection taken on the line 3-3 of Figure 2.

The back support consists of a flexible steel plate 1, mounted forexample in a chair frame 2, the back of which is closed by a back plate6. The lower edge of the steel plate 1 is fastened around a bolt 3 andat the top the upper end is fastened around a bolt 4 slidable in avertical groove 5, so that the plate has a certain latitude of up anddown sliding movement when the curves thereof are regulated.

When the back is adjusted in accordance with a persons back lines, thelower part of the plate 1 must be more or less convex and its upper partmore or less concave (or if necessary straight). Convexity and concavityis regulated by means of two screws 7 and 8 which are moved in and outby means of nuts 11 and 12 respectively. The screws '7, 3 have securedat their outer ends crossbars 9 and it), which support the plate 1transversely, the crossbars 9, being provided with hooked ends 9a andltla respectively which grip around the side edges of the plate 1. Thescrews 7, 8 also extend through holes in transverse plates 15 and 16respectively which are of channel-form in cross section and rest againstthe side rails 2 and the back plate 6 of the chair frame. The plates 15and 16 are adjustable vertically so that the ridges or 2 tops of theconvex and concave plate parts may be moved in the vertical direction ofthe plate so that the curves of the plate and the transitioncurvebetween the convex and concave parts can be altered in-the requiredmanner.

The cross-bars 9, '10'are guided in slots 9b, 101) in the sideflanges oftheplate's 1'5, 1'6, aiidin'o'r'der'tb enable verticaliribvemeiits'ofthe nuts11,'1 2,slots 19, 20 are provided in the backplate 6.

To each plate 15 and 16 is fastened a threaded chock which engagesscrews 13 and 14 operable by means of nuts 17 and E8. Rotation of thenuts 17, 1-8 will cause the plates 15, 16 to be raised or lowered andthereby also the screws 7 and 8 and the cross-bars 9 and 10. In thismanner the top points or ridges of the convex and concave parts of theplate 1 are raised or lowered to fit the lines of the back of a seatedperson, and the transition curve between the two curved parts may alsobe adjusted, by moving the supporting bars 9 and lit closer together orfurther apart from each other. Full control of the curves of the backplate 1 is thereby gained and they may be closely adjusted to fit anypersonal back line.

The whole adjustment may be effected quickly by means of the four nuts11 and 12 and 17 and 18. The back support may be mounted to swing withina limited angle, in the vertical plane, in a chair frame, so that thecant of the back support may be adjusted while a person is sitting inthe chair or seat. The steel plate 1 may be provided with padding and inthis case a vertical depression or thinning out in the padding may bearranged vertically in the middle of the back so that the vertebrae arenot exposed to pressure. The back support may be mounted so that it canbe raised or lowered in the chair frame.

It will be appreciated that constructional detail concerning the chairor seat frame in which the back is fitted may be altered in many ways,the regulation of the ridges of the convex and concave plate partsthereof and the regulation of the transition curve between these twocurved parts being the essential features of the invention.

What I claim and desire tosecure by Letters Patent is:

1. A back support for chairs and the like, consisting of a relativelystiff back plate mounted in a chair frame, said back plate being capableof adjustment to the back line of a user, said plate having a lowerconvex part and an upper concave part, screw means for adjusting theconvexity and concavity of said parts and means for adjusting theposition of the ridges of the convex and concave parts, said screw meansbeing adjustable in the same direction to control the transition curvebetween said parts of the plate, vertically slidable plates of channelcross section mounted in the chair frame and carrying said screw meansfor adjusting the convexity and concavity of the back plate, cross-barsforming part of said screw means, hooked ends to said cross-bars adaptedto grip the side edges of the back plate and form a support therefor,said slidable plate being provided with side flanges and said flangeshaving slots therein to serve as a guide for the said crossbars.

2. A back support for chairs and the like comprising a relatively stitfback plate mounted in a chair frame, said back plate being capable ofadjustment to the back line or" a user and having a lower convex partand an upper concave part with ridges defining the same, screw means foradjusting the convexity and concavity of the said convex and concaveparts and means for adjusting the position of the ridges of the saidconvex and concave parts in a vertical direction, said screw means beingadjustable in the same direction to control the transition between theconvex and concave parts of the plate and including supporting crossbars at their outer ends adapted to support the back plate transversely,the said supporting cross bars having hooked ends adapted to grip theside edges of the back plate.

3. A back support for chairs and the like comprising a relatively stillback plate mounted in a chair frame, said back plate being capable ofadjustment to the back line of a user and having a lower convex part andan upper concave part with ridges defining the same, screw means foradjusting the convexity and concavity of the said convex and concaveparts and means for adjusting the position of the ridges of the saidconvex and concave parts in a vertical direction, said screw means beingadjustable in the same direction to control the transition between theconvex and concave parts of the plate, said plate being provided withpadding which is vertically thinned out centrally thereof.

References Cited in the file of this patent UNITED STATES PATENTS958,356 Bode May 17, 1910 1,264,265 Brusius Apr. 30, 1918 1,677,584Cronwell July 17, 1928 1,937,920 Smith Dec. 5, 1933 2,359,318 Lay et a1Oct. 3, 1944 2,549,902 Hibbard et al. Apr. 24, 1951 2,550,831Lingenfelter May 1, 1951 FOREIGN PATENTS 2,598 Great Britain 1899

